1. Field of the Invention
This invention relates to image generation and more particularly to a color filter system for CCD or APS devices using Red-Green-Blue (RGB) color separation in order to provide color images.
2. Description of the Related Art
Traditionally, the Red-Green-Blue (RGB) separation of color in electronic imaging is done in a variety of ways. In one system, electronic imaging is performed by the use of fixed filters over three separate imagers. Problems sometimes arise with this configuration, as there may be some mis-registration between each of these three separate imagers. In fact, when multiple imagers are used, a high degree of registration between the separate imagers is required.
Another way to perform RGB color separation is to use time multiplexed filters imposed over a single imager. In this system, separate filters provide a series of time exposures to single imagers. The resulting separate images are combined to provide a resulting color image. Lastly, another method by which to achieve RGB color separation is with the use of three colored (or four pixel blocks for symmetry) arrays of pixel sized filters covering a single imager.
Each of these prior ways of achieving RGB color separation has its drawbacks. With the separate imagers, the optics is complicated and, as mentioned previously, high registration requirements are imposed upon the system in order to ensure clarity of the ultimate image. With the other systems, filter wheels are expensive and any camera using such a system is bulky and more unwieldy than if the filter wheels were absent. Using a fixed pixilated color filter generally reduces the resolution of the ultimate image by reducing its pixel density. Additionally, color aliasing is inadvertently introduced which produces disturbing or distracting images in patterned scenes or scenes where high contrast lines are in motion across the field of view.
Consequently, it can be seen that the art still demands, and looks for, an RGB color separation system that overcomes the drawbacks of the prior art.
The present invention realizes an efficient, lightweight, and robust means by which RGB encoding of image data without loss of pixel resolution is achieved.
The present invention provides a system for providing high-resolution color separation in electronic imaging. A Red-Green-Blue (RGB) color strip filter system (or otherwise) is used over an electronic imaging system such as a charge-coupled device (CCD) or active pixel sensor (APS). The color filter is generally modulated over the imaging array at a rate four times the frame rate of the imaging array. In so doing, the underlying imaging elements are then able to detect four separate color-separated images which are then combined to provide a color-accurate frame which is then recorded as the representation of the recorded image. High pixel resolution is maintained. Registration is obtained between the color strip filter and the underlying imaging array through the use of electrostatic comb drives in conjunction with a spring suspension system. The spring suspension system aligns the color strip filter (which is held by a frame) over the imaging array in the first and neutral position. The frame with the color strip filter is then snapped to an up position, and then to a down position before returning to the neutral position. In this way, a cycle is presented over the imaging array so that each individual color filter is presented to an underlying image sensor element one time for each frame of the entire imaging array. In-situ encoding of the filter rows is made by overlays or otherwise that may only be necessary on a few of the rows in order to preserve the image and reduce the pixel losses due to such overlays.
A micro-machined (MEMSxe2x80x94Micro Electro Mechanical Systems) modulator of an RGB strip filter provides the results currently lacking in the art. None of the above-mentioned shortcomings are present in the chromatic modulator of the present invention. Such drawbacks are avoided, as the various color strips used are generally the width of and register with the active pixel area. They also generally match the width of the intermediate dead space. The color strips are moved back and forth over the optical imaging area a distance that equals the width of the filters and at a rate that generally matches the number of filters, namely four times the frame rate of the imager. In so doing, chroma modulation is achieved for all pixels of an imaging array whether a charge-coupled device (CCD) or active pixel sensor (APS). The chromatic modulator of the present invention may be used in camera recorders, or camcorders, digital cameras, APS color filters, and the like. Generally, optical recording equipment implementing the present invention might be brought to market relatively quickly.
It is an object of the present invention to provide better color imaging for optical recorders such as cameras.
It is yet another object of the present invention to provide better RGB color separation and electronic imaging.
It is yet another object of the present invention to provide better color imaging in a manner that maintains image resolution.
It is yet another object of the present invention to provide a filter exposure density greater than two.
It is yet another object of the present invention to provide high-resolution color imaging in a commercially-achievable manner.